Guanazyl and Guanazilium salt compounds as antifog agents for silver halide emulsions

ABSTRACT

Guanazyl and guanazylium salt compounds are effective antifog agents for silver halide photographic emulsions when reactively associated therewith. Such compounds can be incorporated in the photographic element in reactive association with the silver halide emulsion or in a processing bath prior to or during the development of emulsion layers.

United States Patent [191 Baldassa rri Oct. 7, 1975 l l GUANAZYL AND GUANAZILIUM SALT COMPOUNDS AS ANTIFOG AGENTS FOR SILVER HALIDE EMULSIONS [75] Inventor: Agostino Baldassarti, Savona, Italy [73] Assignee: Minnesota Mining and Manufacturing Company, St. Paul. Minn.

22 Filed: Apr. 29, 1974 [2l] ApplsNo; 465,186

[30] Foreign Application Priority Data May it), I973 Italy 49895/73 [52] US. Cl. .4 96/76 R; 96/109 {51] Int. Cl. 4. 603C [/34 [58] Field of Search 96/l09, I07, 66.5, 76 R [56] References Cited UNlTED STATES PATENTS 3,07 l .465 H1963 Dersch et al 96/109 Primary Examiner-Won H. Louie, Jr Attorney, Agent. or Firm-Alexander, Sill, Steldt & DeLaHunt [57] ABSTRACT 23 Claims, No Drawings GUANAZYL AND GUANAZILIUM SALT COMPOUNDS AS ANTIFOG AGENTS FOR SILVER HALIDE EMULSIONS This invention relates to guanazyl and guanazylium salt compounds as antifog agents for silver halide photographic emulsions.

As it is known. the problem of fog. that is silver reduced in unexposed areas upon development which forms spurious images, is one of the most important problems to be solved in the photographic chemistry. This problem has become more critical since high temperature baths are used containing aldehydes as hard ening agents.

We have now found that guanazyl and guanazylium salt compounds are very effective agents both used in a photographic element reactively associated with the silver emulsion and in a processing bath adapted for use prior to or during development of emulsion layers. They can also be used in combination with high temperature processing baths containing or not aldehydes as hardening agents. Guanazylium salt compounds have proven to be more efi'ective than guanazyl compounds when directly introduced into a bath to be used prior to or during development of silver halide emulsions.

Accordingly. the invention relates in one aspect to a silver halide emulsion having contacted therewith a guanazyl and/or a guanazylium salt compound. In another aspect the invention relates to a silver photographic element having a silver emulsion layer and a guanazyl and/or a guanazylium salt compound in reactive association therewith (tag. in a layer adjacent the emulsion layer). The invention in a further aspect relates to a method for inhibiting fog in a silver halide photographic emulsion which comprises contacting said emulsion with a guanazyl and/or guanazylium salt compound. The invention further relates to an improved method for processing an exposed silver halide element, which includes treating said element with a series of photographic treatment solutions including a development solution, the improvement comprising contacting said element during said processing with a guanazyl and/or guanazylium salt compound, preferably a guanazylium salt compound, said compound being contained in said development solution and/or in a predevelopment treatment solution. In another aspect the invention relates to a processing solution The compounds useful according to the present in vention are preferably those represented by the foilowing formulas:

wherein R is an aryl group;

R, is an aryl group or a heterocyclic group;

R, is an alkyl group or hydrogen; and

X is an anion such as, for example. halogen (e.g.

chloride, iodide) and picrate.

An aryl group as used in the practice of this invention is a preferably phenyl or naphthyl group with substituents, if any, selected from at least one of halogen, alkyl, alkoxy, perflouroalkyl, haloalkyl, nitro and acyl groups. These substituent groups each have no more than six carbon atoms when attached to the phenyl group and no more than two carbon atoms when attached to the naphthyl group. The total number of carbon atoms in R and R, is preferably no more than 12, and for R preferably no more than four carbon atoms. The molecular weight of R and R is preferably no more than 300 and more preferably no more than 200. For R the preferred molecular weight is no more than 60.

The heterocyclic group used in the practice of this invention as group R, preferably has a total molecular weight of no more than 300 and more preferably at most 200. The most preferred group is pyridine. Substituents in the heterocyclic group are preferably limited to those same substituent groups preferred for the aryl group of R and R, as phenyl. Preferred heterocyclic groups are five and six membered rings, the skeletal structure of such rings consisting of carbon, nitrogen, oxygen, sulfur, and selenium with groups consisting of carbon and nitrogen, with at most one oxygen or sulfur atom most preferred.

The guanazyls of the present invention were prepared by known processings (Chem. Review 55, 40] (1955), which are based on the reaction of an aryldiazonium salt with a guanylhydrazone, according to the scheme:

NH li Such a reaction is strongly influenced by the pH- value and conditioned by the use of a suitable solvent. The guanazylium salts thereof were prepared by reacting the guanazyl compounds with a salifying agent (e.g. pycric acid and methylchloride or iodide as known to the skilled in the art).

The conditions adopted in the preparation of specific compounds of the present invention are. however, shown with more details in the following examples.

EXAMPLE 1 I-B-diphenyl-guanazyl 9.3 g of aniline (0.1 moles) were diazotated in 30 ml of concentrated HCl (0.3 moles) and 30 ml of water at -2C with 7.5 g (0.1 1 moles) of sodium nitrite. A solution of guanylhydrazone nitrate, 22.5 g (0.1 moles) in 250 ml of water added with 4 g of NaOH in 50 ml of water and 60 g of sodium acetate in 200 ml of water was prepared apart. The diazonium chloride solution was dropped into the guanylhydrazone solution at 2C. The pH-value of the reaction product was adjusted from 5-6 to l0 with sodium hydrate, thus obtaining the separation of a red dusty solid, which was then filtered, dried in the air and crystallized from ethyl acetate.

M.P.- l 99C with decomposition.

Yield-22 g (85% of the theoretical yield).

EXAMPLE 2 l-(m-trifluoromethyl-phenyl)-3-phenyl guanazyl 32.2 g (0.2 moles) of m-trifluoromethylaniline in 60 ml of HCl and 260 ml of water are diazotated with 13.8 g of sodium nitrite (0.2 moles) at 02C. A solution of 45 g (0.2 moles) of guanazyl-hydrazone dissolved in l of methanol was prepared apart. The aryldiazonium chloride solution was then dropped into the guanylhydrazone solution at 0C. 45 g of sodium acetate in 200 ml of water were then added thereto as a buffering solution and the pH-value adjusted to 8-8.5 with a 30% NaOH solution. A dark solid separated slowly. It was then collected by filtration, washed with water, dried and purified by crystallization.

M.P.179C with decomposition.

Yield-71 g (62% of the theoretical yield).

EXAMPLE 3 1-( pchlorophenyl 3-phenyl-guanazyl 25.5 g (0.2 moles) of p-chloro-aniline in 60 ml of HCl and 60 ml of H 0 were diazotated at 05C with 13.8 g (0.2 moles) of sodium nitrite. A solution consisting of 45 g 0.2 moles) of guanylhydrazone benzaldehyde nitrate in 1 l of methanol was prepared apart. This solution was then cooled at 0C and the aryldiazonium solution, prepared before, dropped therein maintaining the temperature at 0C. 45 g of sodium acetate in 200 ml of water were then added thereto. The pH-value was adjusted from 6 to 8.5 with 30% NaOH. The solid was separated by suction, then washed with water, dried and crystallized from acetic ester.

M.P.-188C with decomposition.

Yield-l8 g (32% of the theoretical yield).

EXAMPLE 4 l-phenyl-3(p-tolyl )-guanazyl 18.6 g (02 moles) of aniline with 60 ml of HCl and 60 ml of H 0 were diazotated with 13.8 g (0.2 moles) of sodium nitrite and the diazo-solution was dropped at 0C into a solution of 47.8 g of p-tolylaldehyde-guanylhydrazone nitrate (0.2 moles) in 2,000 ml of methanol. 45 g of sodium acetate in 200 ml of water were added to the reaction product and the pH-value of the solution, thus obtained, adjusted to 88.5 with 30% sodium hydrate. A powdery product separated. It was then washed, dried and finally purified by crystallization from ethanol.

M.P.-174C with decomposition.

Yield-7.8 g (14% of the theoretical yield).

EXAMPLE 5 l -(p-toly1)-3-phenyl-guanazyl 42.8 g (0.4 moles) of p-toluidine were diazotated and the diazo-solution dropped at 0C into a solution of 90 g (0.4 moles) of benzaldehyde guanyl-hydrazone nitrate in 2 l of methanol. A solution of 90 g of sodium acetate and then 30% NaOH, to adjust the pH to 8.5, were then added to the reaction product, thus obtained. A dark-red powdery product separated. It was then washed, dried and purified by crystallization from ethyl acetate.

M.P.- 144C with decomposition.

Yield-24.8 g (22% of the theoretical yield).

EXAMPLE 6 1-phenyl-3( o-chloro-phenyl )-guanazyl 18.6 g (0.2 moles) of aniline were diazotated and the diazo-solution, at 0C, was added to 51.8 g (0.2 moles) of o-chlorobenzaldehyde guanylhydrazone nitrate in l l of methanol plus 45 g of sodium acetate in 200 ml of water and 30% NaOH to adjust the pH to 1 1. When the diazo-addition approached to the end, an orange-red powdery product started to separate. The raw solid was purified by crystallization from nitromethane.

M.P.-209C with decomposition.

Yield-32 g (53% of the theoretical yield).

EXAMPLE 7 l-phenyl-3-( pnitro-phenyl )-guanazyl 4.5 g of the p-nitro-benzaldehyde-guanylhydrazone base were dissolved in 400 ml of ethanol. The solution was cooled at -5C and a solution of diazonium chloride, obtained by diazotating 2.02 g (0.022 moles) of aniline, dropped therein. The solution, thus obtained, was poured into 4 l of water and its pH-value adjusted to 12 with 30% NaOH. A solid separated. It was then purified by crystallization from nitromethane.

M.P.- l 95C with decomposition.

Yield-2 g (30% of the theoretical yield).

EXAMPLE 8 1-( m'nitro-phenyl -3-phenyl-guanazyl 12 g (0.074 moles) of guanylhydrazone benzaldehyde, as a free base, were dissolved in 200 ml of ethanol and ml of water, cooled at l0C and added with a solution prepared by diazotating 10.5 g (0.076 moles) of m-nitro-aniline in 26.2 ml of HCl. The pH- value was adjusted to 8 with NaOH and an orange colored solid separated rapidly. This solid was then collected, dried and purified by crystallization from ethanol.

M.P.-lC with decomposition.

Yield-12.4 g (54% of the theoretical yield).

EXAMPLE 9 1-3diphenyl-guanazylium-chloride 16.2 g (0.1 moles) of guanylhydrazone benzaldehyde were dissolved in 200 ml of ethanol and I00 m1 of water and processed at 10C with a solution obtained by diazotating 9.3 g (0.1 moles) of aniline in 30 ml of HCl. The pH-value of the reaction product was maintained at 5 and the solution concentrated to approximately one half. A brick-red solid separated. It was then purified by crystallization from chloroform.

M.P.-202C with decomposition.

Yield-17.8 g (59% of the theoretical yield).

EXAMPLE [0 l-3-diphenyl-guanazylium iodide l5.l g (0.05 moles) of LS-diphen-ylguanazyl chlorohydrate (example 9) were dissolved in 200 ml of ethanol and then added with g of potassium iodide. The raw iodide separated upon concentration. The product was then purified by several recrystallizations.

M.P.- l 85C with decomposition.

Yield-l5 g (70% of the theoretical yield).

EXAMPLE I l 1-3-diphenyl-N-methyl-guanazylium-iodide 5.3 g (0.02 moles) of l,3-diphenylguanazyl (example 1) in 60 ml of methanol were refluxed with l4.l g of methyliodide for 5 hours. The product thus obtained was then crystallized from nitromethane.

M.P.-l 86C with decomposition.

Yield-4.05 g (50% of the theoretical yield).

EXAMPLE 12 EXAMPLE l3 l-phenyl-3-(o chlorophenyl)-guanazylium-picrate 3 g (0.0l moles) of l-phenyl-3-(o-chlorophenyl)- guanazyl (example 6) were processed as described in example l2. The product was crystallized from ethanol.

M.P.-203C with decomposition.

Yield-4. l5 g (78% of the theoretical yield).

EXAMPLE l4 l m-trifluoromethyl-phenyl- )-3-phenyl-guanazylium-picrate 3.34 g (0.01 moles) of l-(m-trifluoromethyl)-3- phenylguanazyl (example 2) were processed as described in example 12. The product was crystallized from ethanol.

M.P.-l99C with decomposition.

Yield-4.6 g (82% of the theoretical yield).

EXAMPLE l5 13-diphenyl-guanazylium-picrate 2.66 g (0.01 moles) of l',3-diphenylguanazyl (example l were processed as described in example 12. The product was crystallized from ethanol.

M.P.- l 97C with decomposition.

Yield-4.2 g (85% of the theoretical yield).

EXAMPLE 16 l-( p-chloro-phenyl )-3-phenyl-N-methyl-guanazylium-iodide 3 g (0.0l moles) of l-(p-chloro-phenyl)-3-phenylguanazyl (example 3) in 50 ml of methanol were heated for 7 hours with 10 ml of methyl-iodide. The product was crystallized from ethanol.

M.P.- l 82C with decomposition.

Yield-3.5 g of the theoretical yield).

EXAMPLE l7 l-phenyl-3-(y-pyridine) guanazylium chloride 8.15 g (0.05 moles) of y-pyridinaldehydeguanylhydrazone were dissolved in 20 ml of pyridine and 200 ml of ethanol and further added at 5C with a solution obtained by diazotating 4.65 g (0.05 moles) of aniline in l5 ml of HCl. An orange-red solution having a pH value equal to 6-7 was obtained and an orange-colored crystalline product separated by standing. The product was crystallized from ethanol.

M.P.-222C with decomposition.

Yield-5.1 g (34% of the theoretical yield).

EXAMPLE 18 A highly sensitive silver bromo-iodide emulsion, containing 98.2% bromide moles and l.8% iodide moles, was physically ripened, washed, chemically sensitized and further divided into more parts. A part was kept like it was and the others added with compounds Nos. 1-8 of the present invention in the quantities specified in table 3. The said parts were separately coated on a cellulose triacetate base and covered with a gelatin protective layer. Samples of the material, thus obtained, were exposed fresh or incubated to the light of a tungsten lamp and developed for 3' at 20C with a developer having the following composition:

Methol 22.- g Hydroquinone 8.8 g Sodium sulfite, anhydrous 72.- g Potassium bromide 4. g Sodium carbonate. anhydrous 8.- g

Water to make EXAMPLE 19 a densitometer. The results thereof are shown in table 2.

Samples of the material described in example 18 were exposed to the light of a tungsten lamp and developed with the following developer:

Methol 3 g Sodium sulfide, anhydrous 50 g Hydroquinone 9 g Glutaraldehyde disulfite 13 g Sodium carbonate, anhydrous 50 g Potassium bromide 3 g Water to make 1,000 ml. Acetic acid to adjust the pH to 10. 1

The temperature of the developing bath was 35C and the development time 23 seconds. After development, the material was fixed in a bath including glutaraldehyde having the following composition:

A highly sensitive emulsion, having the same characteristics as that used in example 18, was divided into more parts.

A part was kept like it was without any further addition, the others were added with compounds Nos. 9-17 of the present invention in the quantity specified in table 3. The said parts were then separately coated on a cellulose triacetate base and covered with a gelatin protective layer. Samples of the material, thus obtained, were exposed to a tungsten lamp and processed as those of example 18. The samples, processed either fresh or after aging, were read at a densitometer. The results thereof are shown in table 3.

Sodium sulfite, anhydrous g Sodium thiosulfate pentahydrate 400 g Glutaraldehyde disulfite 13 g Water to make 1,000 mi.

and washed and dried for a total processing time of 90 seconds. The samples, thus obtained, were then read at Samples of either fresh or aged materials of example 18 were exposed to the light of a tungsten lamp and developed for 23 seconds at 35C with a developer, fixed and washed for a total processing time of seconds as in example 19.

The samples, thus obtained, were then read at a den sitometer. The results thereof are shown in table 4.

TABLE 4 Aged 15 h. at Fresh 30% RH. and 72C Relative Relative Compound mM/MAgX Solvent Sensitivity Fog Sensitivity Fog DMF 100 0.42 100 0.40 9 0.5 DMF 85 0.20 87 0.20 10 0.1 DMF 97 0.21 0.10 11 0.1 DMF 104 0.16 101 0.23 12 0.1 DMF 102 0.24 0.21 13 0.1 DMF 100 0.16 97 0,17 14 0.1 DMF 103 0.22 103 0.15 15 0.5 DMF 80 0.18 77 0.17 16 0.5 DMF 97 0.30 95 0.30 17 0.1 DMF 68 0.10 44 0.08

EXAMPLE 22 A photographic developer, having the same composition as that described in example 19, was divided into more parts. A part was used without any further addition. the others were added with the quantities specified in table of the new antifoggants of the present invention. Samples of the 3M Medical X-Ray Type R film of the applicant were exposed to the blue light of a tungsten lamp and then developed for 24 seconds at 35C in the prepared developing baths. After development. the material was then fixed in a bath having the same composition as that used in example I) and washed for a total processing time of 90 seconds. The samples. thus obtained, were then read at a'densitometer. The results thereof are shown in table 5.

The compounds can be introduced into the bath by using a solvent. as in the case of introduction into the emulsion. or not.

The silver halide photographic emulsions of the present invention are silver chloride, silver bromide and silver iodide emulsions and mixtures thereof such as, for example. silver bromoiodide and silver chlorobromide iodide.

Such emulsions may include synthetic polymeric gelatin substitutes or additives. such as dextrane, polyvinyl alcohol, polyvinyl pyrrolidone, partially hydrolized polyvinyl acetate. polyethylacrylate, polymethylmethacrylate. polyamides, etc. The emulsions of the invention may be chemically sensitized with naturally active gelatine. by addition of chemical sensitizers such as thiourea. allylthiourea. thyocyanates, thiosulphates. etc. Sensitization may be effected by the addition of noble metals. such as gold salts. Spectral sensitizers may be employed in emulsions of the invention, such as cyanine and merocyanine dyes. Moreover. the emulsions of the invention may include such additives as color couplers. filtering dyes, surfactants. hardeners. stabilizers, additional fog restrainers. plasticizers. antioxidizing agents, developing accelerators. etc. A photographic element comprises one support such as polyester. cellulose acetate, and the like and at least one layer including a silver halide emulsion layer of the above described type coated thereon. Such element can additionally contain other layers, that is, protective layers. interlayers, antihalo layers. filter layers, etc.

The guanazyl and guanazylium salt compounds of the invention may be conveniently introduced in the form of solutions into emulsions or any other coating composition during preparation thereof. Although it is generally preferred to incorporate the guanazyl and guanazylium salt compounds of the invention directly into emulsion layers. these compounds may also be incorporated into layers adjacent the emulsion layers so that the silver halide emulsions are again in reactive association therewith. The guanazyl and guanazylium salt compounds are preferably introduced into photographic elements reactively associated with the silver halide emulsions in amounts ranging from about 0.05 to 2 mM/M of silver halide and most preferably from 0.1 to 0.5 mM/M of silver halide.

The processing baths of the present invention, as noted previously. may be photographic pre-baths. such as those known to the art to be useful prior to treatment of a silver halide photographic element with a developing solution. Predevelopment baths are usually (but not I necessarily) acidic and may contain hardeners such as aldehydes and the like. The guanazyl and guanazylium salt compounds of the invention may. of course, also be employed in developing baths. Such baths are normally alkaline and include one or more silver halide photographic developing agents such as hydroquinone, metol. metol-hydroquinone, phenidone. hydroquinone phenidone. and various p-phenylene diamine materials. the latter being useful in color development processes. The processing baths of the invention (prebaths and developer baths) preferably include from about 0.05 to l mM liter of solution. The guanazylium salt compounds are most preferably included in quantities ranging about from 0.l to 1 mM liter of solution.

I claim:

1. A silver halide photographic emulsion having in reactive contact therewith at least a fog-inhibiting amount of a guanazyl and/or guanazylium salt compound.

2. A silver halide photographic emulsion having in reactive contact therewith at least a fog-inhibiting amount of a guanazyl and/or guanazylium salt compound respectively corresponding to the formulas:

I Nl'l R-N-N-C N-NH-C/ \NHZ R 1 fill-R 2 R-N-N-c-u-NH-c wherein R is an aryl group;

R is an aryl group or a heterocyclic group;

R is an alkyl group or hydrogen; and

X is an anion.

3. The emulsion of claim 2 wherein said anti-fogging compound is l-3-diphenyl-guanazyl.

4. The emulsion of claim 2 wherein said anti-fogging compound is l-(m-trifluoromethyl-phcnyl)-3-phenylguanazyl.

5. The emulsion of claim 2 wherein said anti-fogging compound is l-(p-chlorophenyl)3-phenyl-guanazyl.

6. The emulsion of claim 2 wherein said anti-fogging compound is l-phenyl-3(p-tolyl)-guanazyl.

7. The emulsion of claim 2 wherein said anti-fogging compound is l-(p-tolyl)-3-phenyl-guanazyl.

8. The emulsion of claim 2 wherein said anti-fogging compound is l-phenyl-3(o-chloro-phenyl)-guanazyl.

9. The emulsion of claim 2 wherein said anti-fogging compound is l-phenyl-3-( p-nitro-phenyl)-guanazyl.

10. The emulsion of claim 2 wherein said anti-fogging compound is l-(m-nitro-phenyl)-3-phenyl-guanazyl.

11. The emulsion of claim 2 wherein said anti-fogging compound is l-3-diphenyl-guanazylium-chloride.

12. The emulsion of claim 2 wherein said anti-fogging compound is l-3-diphenyl-guanazylium iodide.

13. The emulsion of claim 2 wherein said anti-fogging compound is l-3-diphenyl-N-methyl-guanazyliumiodide.

14. The emulsion of claim 2 wherein said anti-fogging compound is l-(p-chlorphenylJ-3-phenyI-guanazylium-pycrate.

15. The emulsion of claim 2 wherein said anti-fogging compound is l-phenyl-3-(o-chlorophenyl)-guanazylil 2 um-pycratc.

16. The emulsion of claim 2 wherein said anti-fogging compound is l-( m-trifluoromethyl )-3-phenylguanazylium-pycrate.

17. The emulsion of claim 2 wherein said anti-fogging compound is l-3-diphenyl-guanazylium-pycrate.

18. The emulsion of claim 2 wherein said anti-fogging compound is l-(p-chloro-phenyl)-3-phenylN-methylguanazylium-iodide.

19. The emulsion of claim 2 wherein said anti-fogging compound is l-phenyl-3-('ypyridin)-quanazylium chloride.

20. A silver halide photographic element having a silver halide emulsion layer and a fog-inhibiting amount of a guanazyl and/or guanazylium salt compound in reactive association therewith.

21. A silver halide photographic element having a silver halide emulsion layer and a fog-inhibiting amount of a guanazyl and/or guanazylium salt compound of formulas respectively corresponding to those of claim 2 in reactive association therewith.

22. The photographic element of claim 21 wherein said guanazyl and/or guanazylium salt compound is included in said emulsion layer.

23. The photographic element of claim 2] wherein said guanazyl and/or guanazylium salt compound is included in a layer adjacent said silver halide emulsion layer. 

1. A SILVER HALIDE PHOTOGRAPHIC EMULSION HAVING IN REACTIVE CONTACT THEREWITH AT LEAST A FOR-INHIBITING AMOUNT OF A GUANAZYL AND/OR GUANAZYLIUM SALT COMPOUND.
 2. A silver halide photographic emulsion having in reactive contact therewith at least a fog-inhibiting amount Of a guanazyl and/or guanazylium salt compound respectively corresponding to the formulas:
 3. The emulsion of claim 2 wherein said anti-fogging compound is 1-3-diphenyl-guanazyl.
 4. The emulsion of claim 2 wherein said anti-fogging compound is 1-(m-trifluoromethyl-phenyl)-3-phenyl-guanazyl.
 5. The emulsion of claim 2 wherein said anti-fogging compound is 1-(p-chlorophenyl)-3-phenyl-guanazyl.
 6. The emulsion of claim 2 wherein said anti-fogging compound is 1-phenyl-3(p-tolyl)-guanazyl.
 7. The emulsion of claim 2 wherein said anti-fogging compound is 1-(p-tolyl)-3-phenyl-guanazyl.
 8. The emulsion of claim 2 wherein said anti-fogging compound is 1-phenyl-3(o-chloro-phenyl)-guanazyl.
 9. The emulsion of claim 2 wherein said anti-fogging compound is 1-phenyl-3-(p-nitro-phenyl)-guanazyl.
 10. The emulsion of claim 2 wherein said anti-fogging compound is 1-(m-nitro-phenyl)-3-phenyl-guanazyl.
 11. The emulsion of claim 2 wherein said anti-fogging compound is 1-3-diphenyl-guanazylium-chloride.
 12. The emulsion of claim 2 wherein said anti-fogging compound is 1-3-diphenyl-guanazylium iodide.
 13. The emulsion of claim 2 wherein said anti-fogging compound is 1-3-diphenyl-N-methyl-guanazylium-iodide.
 14. The emulsion of claim 2 wherein said anti-fogging compound is 1-(p-chlorophenyl)-3-phenyl-guanazylium-pycrate.
 15. The emulsion of claim 2 wherein said anti-fogging compound is 1-phenyl-3-(o-chlorophenyl)-guanazylium-pycrate.
 16. The emulsion of claim 2 wherein said anti-fogging compound is 1-(m-trifluoromethyl)-3-phenyl-guanazylium-pycrate.
 17. The emulsion of claim 2 wherein said anti-fogging compound is 1-3-diphenyl-guanazylium-pycrate.
 18. The emulsion of claim 2 wherein said anti-fogging compound is 1-(p-chloro-phenyl)-3-phenyl-N-methyl-guanazylium-iodide.
 19. The emulsion of claim 2 wherein said anti-fogging compound is 1-phenyl-3-( gamma pyridin)-quanazylium chloride.
 20. A silver halide photographic element having a silver halide emulsion layer and a fog-inhibiting amount of a guanazyl and/or guanazylium salt compound in reactive association therewith.
 21. A silver halide photographic element having a silver halide emulsion layer and a fog-inhibiting amount of a guanazyl and/or guanazylium salt compound of formulas respectively corresponding to those of claim 2 in reactive association therewith.
 22. The photographic element of claim 21 wherein said guanazyl and/or guanazylium salt compound is included in said emulsion layer.
 23. The photographic element of claim 21 wherein said guanazyl and/or guanazylium salt compound is included in a layer adjacent said silver halide emulsion layer. 